Chris Christ of Charleston, SC USA asks: It's possible that the prop has been changed to a larger one for
better low-RPM efficiency and to help maintain engine temp at lower RPMs.
Or, perhaps more pitch as been banged into the original prop. This would
certainly overload the engine at WOT.

Jim Leishman of Nordhavn responds:
The previous owner asking the question about an overheating N46 indicated
that he could get 2400 rpm at full throttle - which indicated that he was
not over propped. If he had stated he was only getting, say 2100 rpm, then
the boat would be over propped which would contribute to the overheating
problem.